Re: ATM [ATM] Collimating, the eccentric way.

["David Harbour" <scarab2@cox.net>]

Nils, and all:

Yes, yes, by all means, have it so, if necessary. But I have always
preferred to make a job simple, keep it simple. "KISS".

It helps to "get in the ball park first", and no, one does not actually need
a straightjacket to get in the ball park first; but then again, neither does
anyone need a laser just to get in the ball park, either.

Squaring on the primary mirror first, and making sure that the diagonal is
not too far from centered in the axis of the focuser (some leeway is
allowed), and most assuredly (try it if you don't think it is true) the
focuser must be mounted at 90 degrees to the optical path of the primary,
unless the secondary is RELOCATED and TILTED to COMPENSATE for it, all help
you to GET IN THE BALL PARK, without lasers or straightjackets. Then,
instead of a straightjacket and blindfold, OR a LASER, all one needs is a
second or third magnitude star, and about 750X, to make a nice little nest
of  CONCENTRIC diffraction rings by using the diagonal's adjusting screws.
The oddest thing is, sometimes when you have just made all components look
concentric (not necessarily including the perimeter of the front surface of
the diagonal) and then go to a second magnitude star with 750X,
miraculously, at least sometimes, the little nest of out of focus rings will
surprisingly appear perfectly concentric, requiring no more tweaking. Maybe
I have magic in my fingertips. My formula, summed up, in "25 words or less"?
By all means:



Concentricy,

Not ellipticity,

Nor electricity,

Perhaps only simplicity.



Not bad, huh? Somebody tromp on me tonight. I feel good for a change. Help
me, Dr. Morbius. "Help, Professor Schwartz- I've fallen and I can't get up!"

(Have actually built a few scopes, actually finished a few mirrors).

>Mike Byorick wrote to Dave Harbour:


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